Foundations of Epidemiology PDF

Foundations of Epidemiology Foundations of Epidemiology Role of Epidemiology in Public Health Practice Activities in Epidemiology Case Concepts in Epidemiology Epidemiology Triangle Epidemics, Endemics, and Pandemics Some D...

Foundations of Epidemiology Foundations of Epidemiology Role of Epidemiology in Public Health Practice Activities in Epidemiology Case Concepts in Epidemiology Epidemiology Triangle Epidemics, Endemics, and Pandemics Some Disease Transmission Concepts Modes of Disease Transmission Chain of Infection Other Models of Causation Levels of Prevention Health Health is defined as the absence of illness. It includes the following six dimensions: 1. Physical: Ability to function properly, including fitness. 2. Social: Ability to maintain satisfying relationships. 3. Mental: Ability to think clearly and reason objectively. 4. Emotional: Ability to cope and adapt. 5. Spiritual: Feeling part of a greater existence. 6. Environmental: Impact of external and internal surroundings. Public Health Objectives: Promote health and extend life Concern: Threats to health in the population Mission: Promotion of the 6 Dimension of Health Population refers to a collection of individuals Public Health Approach: 1. What is the problem? 2. What is the cause? 3. What works? 4. How do you do it? Epidemiology as the Foundation of Public Health Assessment and monitoring of health: Identifying health problems and setting priorities. Formulating policies: Developing solutions to public health problems. Ensuring care for all: Providing cost-effective health promotion and disease prevention services. Public Health Core Sciences: 1. Surveillance: Monitoring specific health situations. 2. Epidemiology: Understanding how diseases originate and spread. 3. Laboratory: Diagnosing and investigating diseases. 4. Informatics: Collecting and using data to solve public health issues. 5. Prevention Effectiveness: Providing economic information to guide policy decisions. Epidemiology Overview Definition: The study of the distribution and determinants of health-related states/events in populations. Investigations: Use descriptive and analytic methods to describe data and evaluate health-related hypotheses. Study Designs in Epidemiology 1. Descriptive Epidemiology: Characterizes health events by person, place, and time.  2. Analytic Epidemiology: Identifies causes and associations using statistical techniques. -------------------------------------------------------------------------------------------------- Distribution is the study of frequency and pattern of health events in the population Frequency – number, and number in relation to the population Pattern – the health-related state or event by person, place, and time characteristics Cause: A specific event/condition that leads to a health outcome. Risk Factor: A condition that increases the probability of a health-related event. Health-related States or Events Disease States: Cholera, influenza, pneumonia, mental illness. Events: Injury, drug abuse, suicide. Conditions: Nutrition, environmental poisoning, seatbelt use. Epidemiologic Activities Identifying risk factors for disease, Evaluating the efficacy and injury, and death effectiveness of prevention and Describing the natural history of treatment programs disease Providing information that is useful Identifying individuals and in health planning and decision populations at greatest risk for making for establishing health disease programs with appropriate Identifying where the public health priorities problem is greatest Assisting in carrying out public Monitoring diseases and other health programs health related events over time Being a resource person Communicating public health informatioCommunicating public health information Types of Epidemiologic Information Public health assessment, causes of disease,  clinical picture, program evaluation (efficacy and effectiveness). Epidemics, Endemics, and Pandemics Epidemic: Health-related event above expected in a defined population. Endemic: Usual, constant presence of a health-related event. Pandemic: Epidemic affecting large populations across regions or continents. Types of Infectious-Disease Epidemics: 1. Common-source Epidemics: Exposure to a common agent (e.g., cholera). 2. Propagated Epidemics: Transmission from one person to another (e.g., tuberculosis). 3. Mixed Epidemics: Starts as common-source and spreads person-to-person (e.g., shigellosis). Case Concepts in Epidemiology Primary Case: First disease case in a population. Secondary Case: People infected by contact with the primary case. Suspect Case: Shows symptoms but not diagnosed. Index Case: First case reported to epidemiologists. Different levels of Diagnosis- SUSPECT or CONFIRMED Case severity is found by looking at several variables that are effective measures of it. a. Length of stay in a hospital b. How disabling or debilitating the illness c. Chances of recovery d. How long the person is ill e. How much care the person need Epidemiology Triangle for Infectious Disease Disease Transmission Concepts 1. Fomites: Objects that can harbor infectious agents (e.g., door handles). 2. Vectors: Invertebrate animals transmitting infections (e.g., mosquitoes). Mechanical Vector Biological Vector 3. Zoonosis: Diseases from vertebrae animals transmitted to humans. 4. Reservoirs: Habitat where an infectious agent lives Symptomatic Asymptomatic 5. Vehicle: Nonliving objects conveying infectious agents (e.g., water). 6. Carrier: Person harboring and spreading an infectious agent without symptoms. a. Active carrier A person with symptoms who spreads the disease. b. Convalescent carrier A recovered person who still spreads the disease. c. Healthy carrier A person without symptoms who spreads the disease.  d. Incubatory carrier A person who spreads the disease before symptoms appear. e. Intermittent carrier A person who spreads the disease only at times. Prevention Levels 1. Primary Prevention: Preventing disease before it occurs (e.g., immunization, sanitation). o Active Prevention: Requires behavior change (e.g., wearing protective devices). o Passive Prevention: No behavior change required (e.g., fluoridated water). 2. Secondary Prevention: Early detection and intervention (e.g., cancer screening). 3. Tertiary Prevention: Reducing disability and aiding recovery (e.g., rehabilitation).